This question is asking you to simplify the expression by combining like terms. That is the only way you will be able to "solve" the question.
Start by rewriting out the question to make your work neat and organized.
(5 - t) + (3t + 2)
Combine like terms.
Like terms are terms that have the same variable or variables attached to them (say for example 4x and 7x, 4mn and 6mn) and the same powers attached to them (say for example x^2 and y^2, j^3 and k^3).
In the question, the like terms are identified as 5 and 2 (first pair of like terms) and -t and 3t (second pair of like terms).
You want to solve the question by combining like terms, so "combine" (add/subtract) the like terms that we just identified.
Start by adding 5 and 2 (first pair) then add -t and 3t. After combining like terms, you will get the answer of 7 + 2t.